1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * efibc: control EFI bootloaders which obey LoaderEntryOneShot var
4 * Copyright (c) 2013-2016, Intel Corporation.
5 */
6
7 #define pr_fmt(fmt) "efibc: " fmt
8
9 #include <linux/efi.h>
10 #include <linux/module.h>
11 #include <linux/reboot.h>
12 #include <linux/slab.h>
13 #include <linux/ucs2_string.h>
14
15 #define MAX_DATA_LEN 512
16
efibc_set_variable(efi_char16_t * name,efi_char16_t * value,unsigned long len)17 static int efibc_set_variable(efi_char16_t *name, efi_char16_t *value,
18 unsigned long len)
19 {
20 efi_status_t status;
21
22 status = efi.set_variable(name, &LINUX_EFI_LOADER_ENTRY_GUID,
23 EFI_VARIABLE_NON_VOLATILE
24 | EFI_VARIABLE_BOOTSERVICE_ACCESS
25 | EFI_VARIABLE_RUNTIME_ACCESS,
26 len * sizeof(efi_char16_t), value);
27
28 if (status != EFI_SUCCESS) {
29 pr_err("failed to set EFI variable: 0x%lx\n", status);
30 return -EIO;
31 }
32 return 0;
33 }
34
efibc_reboot_notifier_call(struct notifier_block * notifier,unsigned long event,void * data)35 static int efibc_reboot_notifier_call(struct notifier_block *notifier,
36 unsigned long event, void *data)
37 {
38 efi_char16_t *reason = event == SYS_RESTART ? L"reboot"
39 : L"shutdown";
40 const u8 *str = data;
41 efi_char16_t *wdata;
42 unsigned long l;
43 int ret;
44
45 ret = efibc_set_variable(L"LoaderEntryRebootReason", reason,
46 ucs2_strlen(reason));
47 if (ret || !data)
48 return NOTIFY_DONE;
49
50 wdata = kmalloc(MAX_DATA_LEN * sizeof(efi_char16_t), GFP_KERNEL);
51 if (!wdata)
52 return NOTIFY_DONE;
53
54 for (l = 0; l < MAX_DATA_LEN - 1 && str[l] != '\0'; l++)
55 wdata[l] = str[l];
56 wdata[l] = L'\0';
57
58 efibc_set_variable(L"LoaderEntryOneShot", wdata, l);
59
60 kfree(wdata);
61 return NOTIFY_DONE;
62 }
63
64 static struct notifier_block efibc_reboot_notifier = {
65 .notifier_call = efibc_reboot_notifier_call,
66 };
67
efibc_init(void)68 static int __init efibc_init(void)
69 {
70 int ret;
71
72 if (!efi_rt_services_supported(EFI_RT_SUPPORTED_SET_VARIABLE))
73 return -ENODEV;
74
75 ret = register_reboot_notifier(&efibc_reboot_notifier);
76 if (ret)
77 pr_err("unable to register reboot notifier\n");
78
79 return ret;
80 }
81 module_init(efibc_init);
82
efibc_exit(void)83 static void __exit efibc_exit(void)
84 {
85 unregister_reboot_notifier(&efibc_reboot_notifier);
86 }
87 module_exit(efibc_exit);
88
89 MODULE_AUTHOR("Jeremy Compostella <jeremy.compostella@intel.com>");
90 MODULE_AUTHOR("Matt Gumbel <matthew.k.gumbel@intel.com");
91 MODULE_DESCRIPTION("EFI Bootloader Control");
92 MODULE_LICENSE("GPL v2");
93